Loud speaker



A ril 27, 1926. 1,582,761

T. W. KIRKMAN.

LOUD SPEAKER Filed March 31, 1924 INVENTOR.

54 fzmwzz mMa BY Z 2 A TTORNEYJT Patented Apr. 27," 1926.

] UNITED STATES muons .w. xrnxman, or new YORK, n. Y. i

i LOUD SPEAKER.

Application filed Ilarch 3 1, 1924. Serial No. 703,012.

, paratus.

One of the more important objects of the invention is to produce improved means for so controlling and modulating the speaking and tone producing qualities of a radio in: strument that itsrange of tone'is increased whereby the loudness as well as the distinct articulations-ofsoundis effected by simple adjustment means.

Anoth'eeimportaht feature of my. invention consists in providing a simple manuallyco'ntrolled means readil accessible to the operator whereby thespea er may be quickly adjusted to secure the maximum tonaldistinctness within the desired range of loudness with which the instrument is 'to be operated. To'that end the pole pieces and the magnetsy'stem are assembled with a unitary construction capable of being*ad-' justed, within minutest variations, towards and from the diaphragm of the receiver.

Another of the more. important features of my, invention resides in the simplicity of the device as a whole, that is, not only inthe casing itself, which may be stamped up from metal parts, but also in the mechanism which effects the speaking or tone producing qualities. The device itself is not only simple from the'standpoint of the minimum number of parts contained but also simple from thestandpoint of cheapness and ease of manufacture;

One'of the chief sources of loud speaker troubles is due to the fact that the coveris removed by amateurs with a view of inspect ing the interior thereof. It is therefore another important feature of my invention to provide a suitable seal to detect tampering with the instrument and to so locate this seal that it will not be visible or unsi htly.

The accompanying drawings il ustrate the preferred form of the apparatus but it is to with the horn thereof be expressl yiunderstood that certain changes 1n the construction, adjustment and use thereof may be made without departing "fromlthe s irit and scope of the invention.

. Fig. 1 ilustrates a longitudinal section taken through the loud speaking receiver partly in section and partly broken away.

Fig. 2 is a cross section of the loud speaker taken on the line 22 of Fig, 1.

Fig. 3 is a longitudinal section of the binding posts and the, insulating sleeves carrying said post-s, said section being taken on the line 3-3 of Fig. 1. a

Fig. 4 is a plan view of the non-magnetic d;sk located on'top of the laminated magnets which is'employed with a similar disk below the magnets to bind the latter together into one unitary construction.

Flg. 5 is a plan view of the lower nonmagnetic disk Fig. 6 is a longitudinal section of the lower part of the loud speaker illustrating a m'odified form of means forvarying the distance between the pole pieces and the diaphragm of theloud speaker.

Fig. 7 is a longitudinal section of the lower part .of the loud speaker showing a" cup 10 is provided with a bottom 11 and also with a flange 12 projecting laterally from the upper edge thereof. The bottom is provided with a central perforation 13=to receive means, such as a post 14,-for adj ustably supporting the mechanism'to be housed in the cup or casing 10. V The body is also provided with perforations 15 and 16 for receiving insulating bushings 17 and 18 for the binding posts. To the bottom of the cuplO is secured, preferably by a plurality of rivets 19, a suitable base 20 com rising upper and lower telesco i'ng shel members 21 and 22, each of which is preferably stamped up from a single sheet of material. These shell members are perforated, as indicated at 23 (see Fig.

' 6) to enable the supporting post 14 and the insulating bushings l7 and 18 to pass therethrough.

The cup 1s also provided with a cover 24 comprising the offset horizontal portions 25 and 26, askirt 27 projecting downwardly beyond the flange 12 and a central tubular member 28 adapted to receive the amplifying horn 29 of the instrument. Secured between the'horizontal portion 26 of the cover and the flange 12 of the cup is the usual vibratory diaphragm 30.

Coming now to a description of the magnets and other apparatus designed to cooperate with the diaphragm as well as the adjustment features associatedtherewith, there is shown, for the purpose of illustrating my invention, a pair of magnet coils or windings 31 and 32 which are carried upon the vertical legs 33 and 34 of the core pieces while the other ends 35 and 36 of the core pieces are directed outwardly and anchored by means of screws 37 and 38 between an upper ring or disk 39 of non-magnetic material'and the laminated segmental magnets 40 .and 40 through which the screws 37 and 38 also project. The screws 37 pass through the elements 40 and the screws .38 through the segments 40". Below the elements 4O40 is a second non-magnetic disk 41 preferably somewhat thicker than the disk 39 to provide, among other things, suitable screw-threaded perforations to receive the screw-threads upon the lower end of the screws 37 and 38 previously referred to. It will therefore be seen that the laminated magnets 4040 are clamped between the disks 39 and 41 by means of screws 37 and 38. The magnets are preferably slightly less in diameter than the disks 39 and 41.

The upper non-magnetic disk 39 is provided with a central cut-away portion 42 for the purpose, among other things, to receive the vertical legs 33 and 34 of the core pieces and also to facilitate the connectionof the ends of the coils of the magnets 31 and 32 to the binding posts or terminals'43 and .44 which are suitably anchored, through the bushings 17 and 18, to the lower disk 41 as clearly illustrated in Fi s. 2 and 3. -The laminated magnets are also provided in assembled position with a central cut-away portion corresponding in shape and contour to the cut-away opening 42 in the u per non-magnetic disk 39., The lower dis is provided with two openings 45 and 46 in which theinsulating bushings 17 and 18 are anchored. These bushings, as before stated, carry the binding posts 43 and 44. Preferably, the perforations 45 and 46 are eccentrically located in the disk 41. The latter is provided with the central supporting post 14 which may be secured thereto in any desired manner, preferably by swivelling. as illustrated. The post 14is reduced at 47 where it passes through the disk 41 so as to provide a shoulder upon which a small wash'er 48 is supported and between this washer 48 and the disk is a resilient member 49, the object of which is to take, up any vertical play between the member 41 and said post. The up er end of the reduced portion 47 is brade :over the upper surface of the disk 41.

As illustrated in Fig. 1, the lower end of the post 14 is forked and is provided with a. pin 50 assing through an inclined slot 51 in the ad usting lever 52... The outer end of the lever 52 is provided with an adjusting nut 53 having a bearing 54 journaled in the base 20 of the loud speaker It will, therefore, be readily apparent that upon the manipulation of the adjusting nut 53 the laminated segments 4O-+40 disks 39 and 41, and magnet coils 31 and 32 will be adjusted upwardly or downwardly in the cup or casing 10 relative to the diaphragm 30.

The disks 39 and 41 are both provided at their peripheries with a plurality of substantially arcuate cut-away portions 55, thus leaving a plurality of tongues 56 which, in

the process of manufacture, are spread facture of the-cup and also to avoid any lateral vibration of the parts in operation due to wear.

In Fig. 6 I have ,illustrated a modified form of means for tuning the instrument. In this case the post 14 is pivoted to a lever 57 which is suitably fulcrumed at 58 in the base. The outer end of this lever 57 is provided with a lateral extension 59 removably connected to the adjusting'screw 60, the latter being screw-threaded to a bushing 61 fixed in the base 20 of the instrument.

In Fig. 7 I have illustrated a further modified form of tuning mechanism 'in which the lower end of the supporting post 14 is provided with a screw-thread adapted to be engaged by central screw threads on the worm wheel 62. This worm wheel is engaged by and operated by means of a worm located upon the inner end of the rod 63. The outer end of the rod 63 is provided with a knurled handle 64 for rotating the worm. The thrust of the worm wheel is tak -n up or absorbed by the downwardly and laterally projecting portions 65 and 66 cf the shell member 21. It will therefore be seen that upon imparting a rotational movement in one or the other direction to the knurled handle 64, a movement will be imparted to the worm wheel 62, the effect of which is to raise and lower the supporting post 14".

To the binding posts 43 and 44 are connected the lead wires 67 and 68 held in position thereon by nuts 69 and 70.

For securing the cover 24 to the cup 10, I preferably employ a plurality of bolts 71 which pass through the horizontal portion 26 of the cover and are screw-threa'ded/ to the flang'e- 12 of the cup. The lower pro-' jectlng end of each bolt 71 is located between the skirt 27 and the upper portion of the cup 10. This construction enables a suitable seal 72, clearly illustrated in Fig. 1, to be 73 preferably circular 1n shape.

I have illustrated herein what I now consider to be'the preferred form of my inventioh but it is to be expressly understood that I do not limit myself thereto as other embodiments may be resorted'to and minor changes made withoutdeviating from the true spirit and scope of my invention.

What I claim is:

1. An instrument of the class described comprising a casing, a diaphragm, mechanism in said casing for efl'ectlng a magnetic pull on said diaphragm, in combination with means for effecting an adjustment of said mechanism towards and from sald diaphragm comprising an adjusting -member swiveled to said mechanism and provided with means to take up the play between said member and said mechanism, and res1l1ent means on said mechanism cooperat ng with the walls of the casing to take up the play therebetween.

2. An instrument of the class described comprising a casing having a s de wall and also having a bottom with a plurality of perforations therein, a diaphragm secured to the casing, in comblnatlon with mecha nism for effecting a magnetic pull on said diaphragm comprising a plurality of permanent magnetic elements having their like] poles arranged adjacent to each other, a nonmagnetic plate located on top of said segments, a non-magnetic. plate located below said segments, a pair" of magnet coils, core pieces having vertical legs upon which said coils are wound and also having horizontal arms positioned between said top plate and said magnetic elements, means for securing said core pieces, said plates and elements rigidly to eachother, means for adjusting said mechanism upwardly and downwardly to vary the distance between the core pieces and diaphragm, means for preventing relative rotation between said mechanism and casing, and means for preventing lateral movement of said mechanism relative to said casing.

3. An instrument of the class described comprising a casing having a side wall and net means for clampin also having a bottom with a plurality of perforations therein, a diaphragm secured to the casing, in combination with mechanism for eifecting'a magnetic pull on said dlaphragm comprising "aplurality of permanent magnetic elements having their like poles arranged adjacent to each other, a

non-magnetic plate located on. top of Said segments,

a non-magnetic plate located below said segments,'a pair of magnet coils, core pieces havingivertical legs upon which said coils are wound and also having horizontal arms positioned between said top plate and said magnetic elements, means for securing said core pieces, s'aid'plates and elements rigidly. to each other and means for adjusting'said mcchanismupwardly and downwardly to vary the distance between the core pieces and dia hragm.

. 4. An instrument 0 the class described comprising a casing, a diaphragm, mechanism in said casing'for effecting a magnetic pull on said diaphragnnin combination with means for effecting an adjustment of said mechanism towards and from said diaphragm, meansron said mechanism cooperating with means on said casing-for preventing relative rotation of the former with respect to the latter and resilient means on said mechanism cooperating with the walls- .of the casing to prevent relative lateral movement of the former with respect to the diaphragm.

5. An instrument of the character de scribed, comprising 'a diaphragm, core pieces, coils for said core pieces connected to the exciting circuit, a permanent magnet in magnetic contact with said .core pieces for effecting a permanent magnetic pull of the core pieces upon said diaphragm, said magnet coniprising a plurality of permanent magnetic elements having their like poles arranged adjacent to each other, a non-magnetic plate located below said ma et, a nonmagnetic plate located on top 0 said magsa1d core pieces, magnet and said p ates to each other said and means for adjusting said magnet and said plates, said core pieces and said clamping means longitudinally to vary the gap between the latter and the dia hragm.

6.. An instrument of the c aracter de-. ;;s cr1bed, comprlsmg a caslng, a diaphragm,

core pieces, coils o r said core pieces connected to the exciting circuit, a permanent magnet in magnetic contact with said core pieces for effecting a permanent magnetic pull of the core pieces upon said diaphragm,

' means for clamping said core. pieces and said magnet to each other, means for adj usting said magnet, said core pieces and said clamping means longitudinally to vary the gap between the latter and the diaphragm, and means carried by the clamping means cooperating with said casing to prevent lateral and rotational movements of said core pieces with respect to the diaphragm.

7. An instrument of the character; de-

scribed, comprising a diaphragm, corepieces, coilsfor said core pieces connected to the exciting circuit, a permanent magnet comprising groups of magnetic elements clamped together and having like poles lo cated adjacent to one another, said perma- I nent magnet being clamped in magnetic contact with said core pieces for effecting a permanent magnetic pull'of thecore pieces up on said diaphragm, means for rigidly sesuring said-core pieces and magnetic elements to one another, and means for adjusting said core pieces to vary the gap between the same and the diaphragm.-

8. In an instrument of the character described, a diaphragm, mechanism for effecting a magnetic pull upon said diaphragm, comprising magnetic coils, a non-magnetic plate, binding posts passing through but carried by said plate, bushings surrounding said binding posts to insulate the latter from said plate, the upper ends of said binding posts-being polygonal in shape, and a non-' conducting member provided with spaced polygonal. perforations shaped to fit over the polygonal portion of said posts to prevent the turning of the latter in securing and removing the same to and from said plate.

9. A; loud speaker, comprising a diaphragm, and mechanism for effecting a magnetic pull upon said diaphragm comprising magnetic coils including a non-ma netic plate, binding-posts for the termina s of said, coils carried by said plate, means for insulating said posts from said plate, and

means for preventing said posts from rotat ing in securing the same to said plate.

10. A loud speaker, comprising a diaphragm, mechanism for efiecting a magnetic i usting member.

pull upon said diaphragm, binding posts carried by and secured to said mechanism, means for insulating said binding posts from said mechanism, and means for preventing relative rotation of said binding posts .and said mechanism in securing the former to and removing the same from the latter.

11. A loud speaker casing comprising a cup havinga flange at its. top, a diaphragm, a cover, and means for securing said cup, diaphragm and cover-to each other comprising screws passing through the cover, diaphragm and flange'into screw-threaded engagement with said flange, a molding element of soft metal with a low melting point surrounding the projecting end of one or more of said screws, and asealing material molded by said element around the projecting end of the screw.

12. An instrument of the class described comprising in combination a casing, a diaphragm, mechanism in said casing for .effecting a magnetic pull on said diaphragm. and resilient means on said-mechanism coopcrating with the walls of the casing to take up any play-therebetween.

13. ,An instrument of the class described comprising a casing, a diaphragm, mechanism in said casing for effecting a magnetic pull on said diaphragm, in combination with means for effecting an adjustment of said mechanism towards and from said diaphragm comprising an adjusting member swiveled to said mechanism and provided with means to automatically take up the lay between said mechanism and said ad- In testimon whereof, I have hereunto set my hand t is 29th day of March, 1924.

THOMAS w. KIRKMAN. 

